This invention relates generally to filters for separation of liquids from suspensions. More particularly, the present invention relates to disc filters for separation of liquids from suspensions, in particular fiber stock suspensions, having several filter elements which include a frame over which a filter medium is mounted.
In one type of conventional disc filter, the filter includes a filter vat containing the suspension to be filtered and a substantially tubular filter core, or rotor. Sector-shaped filter elements are held by radially extending holding devices and guides that are fixed to the filter core. These filter elements could also be fixed to a disc filter with a rotor. The filter element includes a frame having frame portions including a neck that could be flared or straight, along the leading and trailing edges, and at the radially outer side. The filter media is a porous bag that is shrunk onto the frame, thereby defining the two outer filtration surfaces of the filter element. The bag is fixed at the lower end by holding plates. The sector-shaped filter elements are slid radially inward into the guides and the individual filter elements are connected to each other at the outer circumference by holding devices. Accordingly, the filter elements are relatively cumbersome and heavy and may only be replaced during relatively long machine shutdowns. In addition, the entire filter media must be replaced if either of the filtration surfaces is damaged.